EP0154832A2 - Dekontamination durch Elektrolyse - Google Patents

Dekontamination durch Elektrolyse Download PDF

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Publication number
EP0154832A2
EP0154832A2 EP85101645A EP85101645A EP0154832A2 EP 0154832 A2 EP0154832 A2 EP 0154832A2 EP 85101645 A EP85101645 A EP 85101645A EP 85101645 A EP85101645 A EP 85101645A EP 0154832 A2 EP0154832 A2 EP 0154832A2
Authority
EP
European Patent Office
Prior art keywords
decontamination solution
metal ions
solution
passing
porous
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP85101645A
Other languages
English (en)
French (fr)
Other versions
EP0154832A3 (de
Inventor
Alexander Peter Murray
Thomas Stephen Snyder
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
CBS Corp
Original Assignee
Westinghouse Electric Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Westinghouse Electric Corp filed Critical Westinghouse Electric Corp
Publication of EP0154832A2 publication Critical patent/EP0154832A2/de
Publication of EP0154832A3 publication Critical patent/EP0154832A3/de
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/04—Treating liquids
    • G21F9/06—Processing
    • G21F9/12—Processing by absorption; by adsorption; by ion-exchange
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/001—Decontamination of contaminated objects, apparatus, clothes, food; Preventing contamination thereof
    • G21F9/002—Decontamination of the surface of objects with chemical or electrochemical processes
    • G21F9/004—Decontamination of the surface of objects with chemical or electrochemical processes of metallic surfaces
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F3/00—Electrolytic etching or polishing
    • C25F3/02—Etching

Definitions

  • This invention generally relates to decontamination procedures for the riddance of radioactive elements from containers in nuclear reactors; more particularly, it concerns eliminating deposits which contain radioactive elements which gradually build up in the cooling systems of nuclear reactors.
  • a decontamination solution which is an aqueous solution of a chelate, such as ethylenediaminetetraacetic acid (EDTA), and a solvent agent, such as a mixture of oxalic acid and citric acid.
  • EDTA ethylenediaminetetraacetic acid
  • the chelate forms a complex with the metal ions from the deposits and reacts with them, and, thus, preventing them from precipitating out of the solution at another location in the cooling system.
  • the decontamination solution is circulated between the cooling system and a cation exchange resin.
  • the chelated metal ions are deposited on the cation exchange resin, freeing the chelate to solubilize additional metal ions in the deposit.
  • the difficulty with this prior art decontamination process is that both the chelates and the cation exchange resin compete for the metal ions. As a result, the metal ions do not readily leave the chelate and attach themselves to the ion exchange column. This means that long resin contact times are required, and that the ion exchange column effluent may contain relatively high metal ion concentrations. For example, an effluent concentration of about 200 to about 250 ppm of iron and about 20 to about 30 ppm of cobalt is typical for a decontamination solution consisting of 0.2% EDTA, 0.15% citric acid, and 0.15% oxalic acid.
  • the metal ions are removed by passing the decontamination solution through a porous DC electrode. Achieved in this manner are a higher DF and lower solution radiation levels, offering a substantial advantage in the ease with which the equipment can be handled and disposed of.
  • the process and apparatus of this invention are also faster than prior art systems because the lower metal ion concentration produces a faster metal ion dissolution rate from the deposits. As a result, less valuable down time is needed for decontamination.
  • the invention in its broad form comprises a method of decontaminating metal surfaces which have a radioactive coating thereon which contains metal ions, comprising: (A) passing an aqueous decontamination .solution containing at least one chelate for said metal ions over said coating to solubilize said metal ions; (B) passing said aqueous decontamination solution through a porous DC electrode to remove said metal ions from said solution; and (C) again passing said aqueous decontamination solution over said coating.
  • a further advantage of the invention is that the porous electrode reduces the ferric ion to the ferrous ion, which is much less corrosive.
  • the ferrous ion is a reducing agent and helps to dissolve the metal ions in the lattice by a single electron transfer process, thereby rendering soluble the oxides that make up the bulk of the deposits.
  • the ferric ion in the lattice is reduced to the ferrous ion which is more soluble than the ferric ion.
  • the removal of the metal ions results in a more uniform dissolution rate of the metal ions in the deposits so there is less corrosion of the metal surfaces in the cooling system and they are less pitted at the end of the decontamination process.
  • the decontamination solution in feed tank 1 is forced through line 2 by pump 3 into the apparatus to be decontaminated or a tank containing the apparatus to be decontaminated 4.
  • the decontamination solution is then forced through line 5 by pump 6 into line 7. If valve 8 is open and valve 9 is closed, the solution passes through line 10 into electrolysis unit 11 then back to tank 1 through line 12. If valve 8 is closed and valve 9 is open, the solution is forced through ion exchange column 13 by pump 14 before passing through electrolysis unit 11 and back to feed tank 1.
  • the process of this invention applies any decontamination solution which contains a chelate for metal ions.
  • Chelates are complexing agents generally having an equilibrium constant for metal ions of greater than about I01 8 .
  • Examples of such chelates include EDTA, trans, 1,2-diaminocyclohexanetetraacetic acid (DCTA), oxybis (ethylenediaminetetraacetic acid) (EEDTA), and nitrilotriacetic acid (NTA).
  • a typical decontamination solution will also contain one or more solubilizing agents. These are generally weak organic acids, such as citric acid or oxalic acid.
  • the electrodes used in the electrolysis unit can be made of stainless steel, "Inconel” (trademark) alloy, nickel, or any other suitable conductor. Stainless steel is preferred as it has good corrosion resistance and is readily available.
  • the electrode must be porous, and is in the form of particles or a mesh. A mesh is preferred as it has a higher surface area and a higher electric gradient. If particles are used they can be packed or in the form of a fluidized bed.
  • the electrode is the cathode in the direct current electric circuit of the electrolysis unit.
  • the decontamination solution is circulated between the metal surfaces to be decontaminated and the electrolysis unit. It is preferable to pass the decontamination solution through a cation exchange column before it enters the electrolysis unit in order to reduce the concentration of metal ion entering the electrolysis unit.
  • About 1 gallon of the decontamination solution per cubic foot of mesh in the electrolysis unit is a suitable operating parameter, though more or less could also be used.
  • the electrolysis unit is operated using direct current at about 1 to about 10 volts.
  • the temperature of the decontamination solution need not be adjusted, and it will typically be at about 75 to 150°C.
  • the electrode in the electrolysis unit is exhausted when a pressure drop is detected across it and it must then be replaced.
  • the metal ions on the electrode can be recovered, but .usually this is not worth the trouble and the contaminated electrode is disposed of as solid waste. If recovery is desired it can be accomplished in an inorganic acid or a strong organic acid.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Physics & Mathematics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • General Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Food Science & Technology (AREA)
  • General Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Metallurgy (AREA)
  • Water Treatment By Electricity Or Magnetism (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
  • Electrodes For Compound Or Non-Metal Manufacture (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
EP85101645A 1984-03-01 1985-02-15 Dekontamination durch Elektrolyse Withdrawn EP0154832A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US06/585,062 US4537666A (en) 1984-03-01 1984-03-01 Decontamination using electrolysis
US585062 1984-03-01

Publications (2)

Publication Number Publication Date
EP0154832A2 true EP0154832A2 (de) 1985-09-18
EP0154832A3 EP0154832A3 (de) 1986-04-30

Family

ID=24339896

Family Applications (1)

Application Number Title Priority Date Filing Date
EP85101645A Withdrawn EP0154832A3 (de) 1984-03-01 1985-02-15 Dekontamination durch Elektrolyse

Country Status (7)

Country Link
US (1) US4537666A (de)
EP (1) EP0154832A3 (de)
JP (1) JPS60205300A (de)
KR (1) KR850007162A (de)
CA (1) CA1252415A (de)
ES (1) ES8703211A1 (de)
ZA (1) ZA851098B (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0612863A1 (de) * 1993-02-26 1994-08-31 Rockwell International Corporation Verfahren und Vorrichtung zur Regenerierung eines Reduktionsmittel

Families Citing this family (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4654170A (en) * 1984-06-05 1987-03-31 Westinghouse Electric Corp. Hypohalite oxidation in decontaminating nuclear reactors
USRE34613E (en) * 1985-05-28 1994-05-24 Recytec Sa Process for decontaminating radioactively contaminated metal or cement-containing materials
EP0224510B1 (de) * 1985-05-28 1991-01-16 Recytec S.A. Verfahren zur dekontamination von radioaktiv kontaminierten gegenständen aus metall oder aus zementhaltigem material
US4681705A (en) * 1985-10-15 1987-07-21 Carolina Power & Light Company Decontamination of radioactively contaminated liquids
US4792385A (en) * 1987-11-03 1988-12-20 Westinghouse Electric Corp. Electrolytic decontamination apparatus and encapsulation process
JPH0317288A (ja) * 1989-06-13 1991-01-25 Daicel Chem Ind Ltd スタンパー用電解洗浄液
CH678767A5 (de) * 1989-06-30 1991-10-31 Jozef Hanulik Dipl Chem
US5024805A (en) * 1989-08-09 1991-06-18 Westinghouse Electric Corp. Method for decontaminating a pressurized water nuclear reactor system
JPH0727073B2 (ja) * 1990-03-20 1995-03-29 森川産業株式会社 放射能に汚染された物体の除染方法及び除染装置、並びに同除染に用いられた材料の除染方法及び除染装置
US5078842A (en) * 1990-08-28 1992-01-07 Electric Power Research Institute Process for removing radioactive burden from spent nuclear reactor decontamination solutions using electrochemical ion exchange
CH682023A5 (de) * 1990-10-26 1993-06-30 Recytec Sa
US5292456A (en) * 1992-03-20 1994-03-08 Associated Universities, Inc. Waste site reclamation with recovery of radionuclides and metals
US5306399A (en) * 1992-10-23 1994-04-26 Electric Power Research Institute Electrochemical exchange anions in decontamination solutions
US5832393A (en) * 1993-11-15 1998-11-03 Morikawa Industries Corporation Method of treating chelating agent solution containing radioactive contaminants
US5489735A (en) * 1994-01-24 1996-02-06 D'muhala; Thomas F. Decontamination composition for removing norms and method utilizing the same
US5814204A (en) * 1996-10-11 1998-09-29 Corpex Technologies, Inc. Electrolytic decontamination processes
DE19818772C2 (de) 1998-04-27 2000-05-31 Siemens Ag Verfahren zum Abbau der Radioaktivität eines Metallteiles
US7384529B1 (en) 2000-09-29 2008-06-10 The United States Of America As Represented By The United States Department Of Energy Method for electrochemical decontamination of radioactive metal
TW529041B (en) * 2000-12-21 2003-04-21 Toshiba Corp Chemical decontamination method and treatment method and apparatus of chemical decontamination solution
US6682646B2 (en) 2002-03-25 2004-01-27 Electric Power Research Institute Electrochemical process for decontamination of radioactive materials
US20050230267A1 (en) * 2003-07-10 2005-10-20 Veatch Bradley D Electro-decontamination of contaminated surfaces
EP2596502B1 (de) * 2010-07-21 2020-03-04 Atomic Energy of Canada Limited Dekontaminationssystem für reaktoren und verfahren
US9617646B2 (en) 2012-11-14 2017-04-11 Elwha Llc Comminution water contaminant removal system
JP6434318B2 (ja) * 2015-01-16 2018-12-05 株式会社神戸製鋼所 タンクの除染方法
JP6591225B2 (ja) * 2015-08-03 2019-10-16 株式会社東芝 除染方法
RU2713733C1 (ru) * 2019-06-27 2020-02-07 Федеральное государственное унитарное предприятие "Горно-химический комбинат" (ФГУП "ГХК") Способ дезактивации графитовых радиоактивных отходов

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2077482A (en) * 1980-06-06 1981-12-16 Us Energy Coolant system decontamination
EP0075882A2 (de) * 1981-09-25 1983-04-06 Hitachi, Ltd. Verfahren zum Regenerieren von Reinigungslösungen

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3244605A (en) * 1963-07-05 1966-04-05 Dow Chemical Co Purification of aqueous caustic solutions
US3459646A (en) * 1968-06-25 1969-08-05 Ppg Industries Inc Alkali metal hydroxide purification
US3650925A (en) * 1969-06-02 1972-03-21 Ppg Industries Inc Recovery of metals from solution
US4193853A (en) * 1979-05-15 1980-03-18 The United States Of America As Represented By The United States Department Of Energy Decontaminating metal surfaces

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2077482A (en) * 1980-06-06 1981-12-16 Us Energy Coolant system decontamination
EP0075882A2 (de) * 1981-09-25 1983-04-06 Hitachi, Ltd. Verfahren zum Regenerieren von Reinigungslösungen

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0612863A1 (de) * 1993-02-26 1994-08-31 Rockwell International Corporation Verfahren und Vorrichtung zur Regenerierung eines Reduktionsmittel

Also Published As

Publication number Publication date
KR850007162A (ko) 1985-10-30
EP0154832A3 (de) 1986-04-30
US4537666A (en) 1985-08-27
ES540718A0 (es) 1987-02-01
JPH039438B2 (de) 1991-02-08
CA1252415A (en) 1989-04-11
ZA851098B (en) 1985-09-25
ES8703211A1 (es) 1987-02-01
JPS60205300A (ja) 1985-10-16

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Inventor name: MURRAY, ALEXANDER PETER

Inventor name: SNYDER, THOMAS STEPHEN